This invention relates to a method of producing a window sash and an associated product and more particularly to a window sash that eliminates the need to provide a parting bead.
Conventional window sashes are made by a process which involves several interrelated steps. The first step is to produce framing members that will be used to form the window sash frame. These framing members can be made of aluminum, vinyl or other material. For example, four vinyl extrusions can be used to form a rectangular window sash frame. The four vinyl extrusions typically have mitred corners and are joined by corner keys, welding or other joining methods.
After the window sash frame is formed, the glazing panel (usually a pane of glass) is dropped into the space formed by the four framing members. The glazing is supported by elongated flanges on the inside of each of the framing members. In order to secure the glazing panel in the window sash frame, four separate elongated parting beads are placed on top of the glass panel, on the opposite side of each of the elongated flanges. The parting bead is secured to the glazing panel by adhesive glazing tape or a rigid polyvinyl chloride ("PVC") employing soft vinyl fingers known to those skilled in the art as dual durometer.
There are several disadvantages associated with the parting bead. If the window sash is installed in a building opening with the parting bead facing the outside, it is easy for a thief or other intruder to forcibly separate the parting beads from the window sash and remove the glazing so as to create access into the building in which the window sash is mounted. If the parting bead faces the inside of the building, the aesthetics of the window are affected by the presence of a line in the window sash frame Furthermore, with the parting bead on the inside there is an increase of water and air filtration into the home. When a parting bead is secured by using a glazing tape, it is very costly to reglaze the window sash and in addition the glazing can shift in the sash which can cause stress breakage in the glazing. Finally, there is a vinyl window industry test, known to those skilled in the art as Test No. D-4099 for de-glazing. Most glazings secured by a parting bead with a dual durometer will fail this test.
There have been some suggestions in the prior art as to the formation of window sash frames without parting beads. U.S. Pat. No. 3,455,080 discloses plastic extrusions used for window frames. The extrusion is made having a channel with flexible ribs and portions having respective teeth-like projections. The portions are joined by a frangible connecting web. The window sash formed with the extrusions is assembled as shown in FIG. 4. Three mitred extrusions are placed in a U-shaped configuration and a pane of glass is inserted into the channel portions thereof. After this, pressure is exerted on wall portion to break the web and thus cause the base portions to engage each other by means of the teeth thereon. This also causes deformation of ribs. The corners of the frame are heat sealed or connected with adhesives. The top extrusion is connected to the rest of the extrusions by means of corner keys. See also U.S. Pat. Nos. 3,918,231 and 4,539,243.
Despite the prior art methods and products, there remains a need for an improved method of making a window sash and an improved window sash.